Environmental test chambers are used by designers and manufacturers of printed circuit boards (e.g., boards with electronic components mounted thereon) to subject the circuit boards to thermal cycling so as to determine whether the circuit boards are able to withstand thermal stresses that the circuit boards may encounter during use. Typically, an automatic controller is interfaced to the environmental test chamber to control heating and/or cooling of the air (or other fluid) inside the chamber so that circuit boards placed in the chamber are subjected to the desired thermal testing regimen. Often thermal testing of circuit boards requires a period of days or weeks as the circuit boards are subjected to numerous cycles in which the boards are brought up or down to a desired “soak” temperature, maintained at that temperature for a specified period, and then “soaked” at another temperature. It would be desirable to reduce the time required for thermal testing of circuit boards.